Telephone system



Dec. 26, 1922. 1,440,112

0. SPARKS. TELEPHONE SYSTEM. FILED JULY 1. 191B.

rein.

titans CHARLES SPARKS, OF OAK PARK, ILL ECNUIS, ASSIGNOR TO KELLQGG- S'WITCHIBOARD AND SUPPLY COMPANY, OF CHICAGD, ILLINOES, A GQBPQEATION OF ILLINOIS.

TE -artisan SYSTEM.

Application filed J'uly 1, 1918. Serial No. 242,711.

1 0 all whom it may concern:

Be it l-znown that l UIiiinLnsSrAnKs, a citizenoii the United iii-tates of America, residing in Oak Park, county otCook and State of lllinois, have invented certain new and useful Improvements in Telephone Sys tems, of which the tollowmg 1s a specification. y

My invention relates to telephone systems in which manual link or cord circuits are.

Should the calling subscriber wishto recall after the replacement of his receiver, the

removal of the receiver from the switch hook causes the multiple l'inelamps to be lighted so that the. recall may be seized by the same operator who handled the original ("all or by another operator, either one to the exclusion of the other,' depending on which one seized the recall first. y i

ii. feature of my invention is the provision of means in the cord circuit'whereby the line circuit of the called suliiscriber is disconnected from the connected cord circuit so that upon the removal of the receiver at the called substation. from its switch hook the multiple line sigz nals associated with the :alled line are lighted and the ca-ll'may be answered by the operator who established the original connectionor by any other opmater each" one to the exclusion of the other. a i 3 Another ler-riurc oi? my invention is the provision of means whereby a called subscriber is lfi'cYOHli-Hl from initiating a call ,until after the calling subscriber name placed his receiver so-that int-he eventthat he called subscriber tumbles his receiver in answering a call' momentary closing and opening (Ti the switch hook contacts will not disas'sociate the called subscrihefis line from the connected link circuit. i

lit still further feature of my invention is the provision of means for reinovingthe busy potential from the jack of the called The above features, as well as others, will be the multiple line signals S and S". acks oithe lines are distributed among ditline when the called party signals for disconnection which means is only operative alter the calling subscriber has signaled for disconnection. I I 3 i And still another feature ot my invention is the provision of means in thelink circuit whereby when a called subscriber signals for a call while a cord circuit is still connected to hisline, the seizure of the call by another operator actuates said means to prevent the operator whose cord circuit is still connected to the line from coming in and disturbing the call being handled by the second operator.

more fully hereinafterdescribed in the following. specification.

For a better understanding of my invention," reference may be, had to the accompanying drawing in which 1 illustrate my invention operating ineonneetion with a telephone system.

In the drawing, 1 show a calling substation- A and a called substation. B, the said calling and called substations A andll terminating, respectively, at the exchange in line circuits L and L; the exchange comprise, respectively, the usual line relays LR and LR, cut-oil relays CO and CO, multiple jacks J and J, and

The

of operators may seize the call to the ex- 'clus onot the other operators.

The cord circuit C for interconnecting the substations A and B as calling and called 111185 s provided with an answering plug ;A.P and a calling plug GP. the saidanswering and calling plugs AP and GP being connected by the heavily marked conductors. The answering end ofthe cord circuit C is provided With a sleeve relay SL which is energized when an answering plug AP is inserted into the jack J of the calling line.

The relay SL is provided with a high resistance winding and a low resistance winding,

andupon the actuation of the relay SL the high resistance Winding is shunted and this prevents the sleeve relay from being energized in another cord circuit should another The line circuits L and L at operator attempt to answer the call. An operator at any other cord attempting to seize the call after the first operator has connected to the calling line is prevented from communicating with the subscriber, as the shunt of the low winding of the relay SL of the first cord prevents the relay SL of the second cord from operating. As the sad 0nd operator is not connected to the calling line, due to the relay SL of the second cord remaining at normal, she does not receive an answer from the calling subscriber and withdraws the answering plug of her cord circuit from the connected jack. A super visory relay SR is provided which is ener gized upon the actuation of the relay SL, the said relay SR operating over the line.

. The relay SR, upon actuation, prevents the premature lighting of the answering supervisory lamp AL. A listening relay LS is provided and is actuated in response to the energization of the relay SL to connect the operators set O to the cord conductors. A link disconnect relay LD' is provided which is energized when the calling subscriber replaces his receiver ait'ter finishing conversation to open the link conductors to allow the line circuit of the calling subscriber to restore to normal to permit the calling subscriber to recall. The link disconnectirelay LD also operates when the calling subscriber replaces his receiver and before the called subscriber answers-to disconnect the ringing current from the called line.

An answering meter relay AM is also associated with the answering end or the cord circuit C and is energized upon the actuation of the listening relayLS, and the relay- AM, upon energization, brings about the actuation of the meter magnet MM, which magnet operates the register device. A recall key K is provided, which key may be actuated by the operator to bring about. the actuation of the listening relay LS to coir nect her operators set 0 tothe cord con ductors to answer a recall.

The calling end of the cord circuit- C is provided with a sleeve relay SL ctuated when the calling plug OP is inserted into the-jack J of the called line. The said relay SL, upon energizing. opens the circuit of the listening relay LS, which relay deenergizes to disconnect the operators set 0 from the cord conductors. The relay SL also upon its energization opens the circuit of the answering meter relay AM. A party line ringing key BK is provided for connecting one oi? a plurality of generators. G, G, G and G to signal the called for sub scriber. An interrupter relay IE is energized upon the actuation of the party line ringing key RK, the said relay remaining energized as long as the party line ringing key BK is held in its fully depressed posi tion to give the called subscriber an instan this circuit being through the lower provided which is actuated upon the response of the subscriber at the called-tor substation, should the called subscriber remove his receiver in response to the call signal during a ringing period. The relay RT, upon energization, interrupts the circuit oi'the ringing'control relay RC and the said relay BC in turn disconnects the interrupter T from relay IR to allow the said relay IE to restore to normal. A supervisory relay SR is also providedwhich is actuated upon the response of the called subscriber to interrupt the circuit oi the relay RC should the subscriberat the called for substation remove his receiver during silent period. A calling supervisory lamp CL is provided and is used for the usual supervisory purposes. A link disconnect relay LD is provided which is energized when the called subscriber replaces his receiver upon the switch hook and after the calling subscriber has replaced his receiver upon the switch hook. Relay Ll) inenergizing opens the cord conductors to allow the line circuit of the called subscriber to restore to normal to permit the subscriber at the called substation to recall. A holding relay H is provided, as is also a double wound relay D, for purposes as will be hereinafter fully described.

Having described in general the arrang ment of the circuits and apparatus employed in my invention, I will now describe it more in detail and assumingthat the subscriber at the calling substation A initiates a call,

the removal of the receiver th'ereat brings about the energization of the line relay LR of the line circuit L, and the closing of alternate contact li hts the line lamps'S at a plurality of operators positions. Assuming that it is the operator at cord circuit C that answers the call, the insertion of the answering plug AP into the jack J of the calling line establishes a series energizing circuit for the cut-off relay (it) of the line circuit ii, and the sleeve relay bill. the circuit being traced from battery through the U0 windings 2 and 8 of relay bill, condu r I normal contact 5 of relay Ll), (OllQlllCtOL a, sleeve contacts of the connected plug Al? and jack J, and through the r-rinding oi the cut-off relay CO to ground. The closure of alternate contact 7 of relay SL, upon its en ergization, closes a lower resistance circuit through its winding 2, shunting winding 3, traced from battery winding 2 of therelay SL, 13

its alternate contact l. conductor 4, normal contact 5 ol? relay .lillcoiiductor 3, sleeve contacts to connect the plug All and ad; J, through the Winding of the cut-off relay CO to ground. The high resistance winding 3 of the relay SL is shunted, this arrangement providing for secret service, as a relay SL of a second cord circuit Will not operate in series with the relay CO as the shunt of the lOW winding 2 of the relay SL ot' the first cord circuitrenders the relay 53L ot the second cord inoperative.-

The closing of alternate contact 8 of relay SL establishes an energizing circuit for the supervisory relay SR, traced from battery through the lower winding of relay SR, conductor 9, normal contact 10 of relay Ll), ring contacts of the Connected plug AP and jack 3, through the closed contacts of the substation switch hook, back through the tip con tacts oft theconnected jack J and plug AP, normal contact 11 of relay LD, conductor 12, alternate contact 8 of relay SL, conductor 13, and through the upper winding 01": the relay SE to ground. The opening of normal contact 14 of relay SR prevents the prema ture lighting, of the answering supervisory lamp AL. The ei'iergization of the relay C0 of the line circuit L opens the energizing circuit of the line relay LR which restores to etlace the line signals 5. The closing of alternate contact 15 of sleeve relaySL establishes an energizing circuit for the listening relay LS, traced trombattery through the lower winding 16 of relay LS, conductor '17, alternate contact 15 of relay SI and c n:

ductor 18 to ground at normal contact 19 of the sleeve relay Sli.

The relay LS, upon energizing, closes its alternate contacts 20 and 21 to connect the operations set to the cord. conductors. Should another operator attempt to seize the call after the ope ator associated with the cord circuit C is connected thereto, the low resistance path through winding 2, of he relay Sli prevents the relay SL of the second cord circuit from operating, and the relay LS of the second cord failing to operate does not connect the operat ons set 0 of the second cord across the cord conductors. The second operator failing to receive a response when she ansv knows thatthc call. has been answered by another operator and Withdraws the plug o'l her cord circuit 'li'on'i the multiple jacket the calling line.

'lhe closing of alternate contact 21 ol. the listening relay LS establishes an energizing circuit for the answering meter relay AM, traced from ground atnorn'ial contact 26 of relay SL, over conductor 2'7, through alternate contact 28 of relay SR, conductor 29, normal contact 30 of relay AM, through the winding olttlie relay, conductor 23, alternate contact 21 of relay LS, conductor 25, normal contactSl of ringing control relay 13 C, conductor 32 and through the lower winding of the supervisor y relay tilt to battery. p

The closing otalternate contact 30 of the relay AM establishes a locking circuit'lor itself from ground through its alternate con.- tact 30, through the winding of the said relay AM to batteryover the previously de scribed path. The closing of alternate con tact of the relay AM establishes an energizing circuitfor the meter magnet ll lM traced from ground through said alternate contact 33 and the winding of the magnet MM to battery. The magnet MM energizing causes the register to move one step'to register a call answered by the operator associated with the cord circuit C. i

The operator, having been connectedto the cord conductors, now inquires the Wants ot the calling subscriber at the substation A,

and assuming that it is the'subscriber at the substation B that is wanted, the operator tests the multiple jack J of the called line as to its idle or busy condition, and if the said line is busy, the sleeve er the jack is of a battery potential and the operator will receive an impulse of current through the winding 34 of induction coil 1C and through the winding 35 of the retardation coil BA to ground. This induces an impulse of current into the winding 36 of the induction coil 10 to produce the usual busy click-in the head receiver of the operators set. i i

Assuming that thelineiis idle, the operator inserts the calling plug Cl? into the multiple jack J of the called'line B, closing a series energizing circuit-tor the sleeve relay SL ofthe cord circuit Cand the cutoil relay COT of the line circuit L, the circuit being traced from battery, through the winding of the relay SL', conductor 37, normal contact 38 of relay LD, conductor 39, normal contact 40 of relay H, conductor ll, sleeve contacts of the connected plug CP and jack J, and through the winding of the cut-oil relay CO to ground. The opening of normal contact 19 of the relay SL opens the energizing circuit of the listening relay LS, and said relay LS restoring opens its alternate contacts 20 and 21. to disconnect the operators set 0 from the cord conductors. The opening of alternate contact 21 of the relay LS interrupts the locking (in; cuit of the answering meter relay AM.

The closing of alternate contact 26 of the relay SL' establishes a. circuit for the calling supervisory lamp CL, traced from bat tery through the answering supervisory amp CL, normal contact 42 of relay RC,

conductor 43, conductor as, normal contact 45 of relay Ll), conductor 46, normal con.-

tact 47 of ringing trip relay RT, normal contact 48 of supervisory relay S i, and

conductor 4L9 toground at alternate contact is 26 of relay SL', the said supervisory lamp CL remaining lighted until the operator depresses party line ringing key BK. The operator now depresses the proper ringing key plunger of the party line ringing key to its fully depressed position to' close the end spring contact 50 and to connect the proper ringing generator G, G, G or G to signal the called for subscriber at the substation B. The closing of alternate contact 50 of the end springs brings about the energization of the interrupter relay IR, during the interval that the key is held down, over a circuit traced from battery through the lower winding 51 of the relay IR, conductor 52, alternate contact 50 of the end spring, conductor 43, conductor 44, normal contact of relay LD, conductor 46, normal contact 47 of relay RT, normal con tact 48 of SR, and conductor 49 to ground at alternate contact 26. The closing of alternate contact 53 of relay 1R connects ringing current from the generator G, which we will assume is the generator selected to ring the call bell of the subscriber at substation B, giving an instantaneous first ring to the called subscribers call bell. The closing of alternate contact 54 of relay IR establishes an energizing circuit for the ringing control relay RC, traced from battery through the Winding of the said relay, conductor 55, alternate contact 54 of relay 1R, conductor 44, normal contact 45 of relay LD, conductor 46, normal contacts-47 and 48' of relays RT and SH, respectively, and conductor 49 to ground. at alternate contact 26 of relay SL.

The closing of alternate contact 42 of relay RC establishes a locking circuit for the said relay RC, traced from battery through the winding of the said relay RC. its alternate contact 42, conductor 43, over conductor 44, and over the above-traced path to ground at alternate contact 26- of the sleeve relay SL'. The opening of normal contact 42 of relay RC effaces the calling supervisory signal CL. The closing of alternate contact-56 of, relay BC connects interrupter I to the upper Winding of the interrupter relay IR, the circuit being traced from ground, through the constantly rotating interrupter I, alternate contact 56 of relay RC, conductor 57, and throughthe upper winding 58 of the interrupter relay IR to battery. The relay IR is thus intermittently energized and deenergized to connect ringing current from generator (l to the called line over a circuit tracedfrom the ungrounded pole of the generator G, through alternate contact 59 of the depressed ringing key plunger, conductor 60, through the winding of the ringing trip relay RT, conductor 61, conductor 62, alternate contact 53 of the relay 1R, tip contacts of the connected plug GP and jackJ, through the condenser and call bell at the called substation B, back through ring contacts of the connected jack J and plug GP, through alternate contact 63 of relay IR, conductor 64, through alternate contact 65 of relay RC, and through resistance 66 to battery 67 and ground.

The closing of alternate contact 68 of the interrupter relay IR- transmits a ringing tone to the calling subscriber at substation A, the ringing tone being traced from the low frequency generator Grflwhich is of 16 cycles, over conductor 69, conductor 70, through resistance 71, condenser 72, alternate contact 68 of relay IR, conductor 7 3, alternate contact 74 of relay RC, normal contact 11 of relay LD, tip contacts of the connected plug AP and jack J, through the receiver at the calling substation A, back through the ring contacts of the connected plug AP and jack J, normal contact 10 of relay LD, conductor 9, through the winding of the supervisory relay SR to battery and ground, giving the calling subscriber at substation A an audible signal notifying him that the called subscriber at substation B is being signaled. The called subscriber at the substation B is thus automatically signaled until he answers in response to his call signal, or until the calling subscriber replaces his receiver before the said called subscriber answers.

The non-inductive winding W which is in multiple with the winding of the ringing trip relay ET is only connected to the low frequency of ringing current, say the 16 cycles of current. Should the operator have depressed the ringing key plunger to connect the ringing generator G which we will say is the generator delivering 16 cycles of ringing current, the depression of this ringing plunger will release any other of the ringing key plungers that are in indicating position, the ringing current from the ringing generator G being traced from the ungrounded pole of the generator G through the serially closed ringing plunger contacts of the ringing key BK to the point 75, part of the current passing over conductor 60, through the winding of relay RT, conductors 61, to the point 76, and thence over the conductor 62 through alternate contact 53 of relay IR, tip contacts of the connected plug GP and jack J, through the condenser and call. bell of the called substation, back through ring contacts of the connected, plug CP and jack J alternate Contact 63 of relay IR, conductor 64, alternate contact 65 of relay RC and resistance 66 to battery 67 and ground. The other path for the ringing current extends from vpoint 7 5 over conductor 177, through alternate contact 178 of ringing key plunger, the non-inductive winding WV, and over conductor 61 to the point 7 6 and thence over 1,4ao,11a

conductor 62, over the previously described path to battery 67 and ground. Without this resistance W, should thelow ffrequeiicy current pass through the winding of relay RT, the said relay mightchatter, and there would be a liability of opening the locking circuit of the ringing control relay RC which would bring about the premature disconnection of ringing current from the called line. 1 it Siould the calling subscriber replace his receiver before the called subscriber answers', the supervisory relay SR Will restore, due to the interrupted switch hook contacts the calling substation A. The closing oi. normal contact 14: of the supervisory relay SR establishes an energizing circuit for tie link disconnect relay LD, traced from battery through the winding ofsaid relay, conductor 77, normal contact 14L of relay SR, conductor 78, alternate contact 79 of relay SL, conductors 80 and 81, to ground at alternate contact 19 of relay SL. The

closing of alternate contact 50f relay LD establishes a. substitute circuit for the sleeve relay SL, the circuit having been opened at normal contact 5. The said circuit may be traced from battery, through the lower winding 2 of the relay SL, alternate contact 7, conductor 1, alternate contact 5, conductor 82, normal contact 83 of the key hf, conductor 78, alternatecontact 79, conductors and 81, to ground at alternate contact 19. The opening of normal contact 45 of relay LD opens the locking circuit of the ringing control relay RC, which relay deenergizes to open its normal contact 56 to disconnect the interrupter I from the interrupter relay Til. The relay TR restores to normal, opening its alternate contact 53to prevent further application of ringing, current'to the calledline. The closing of alternate contact 41 5 establishes a circuit for the calling super-v 'visory lamp CL, traced from battery through the said lamp CL, conductor 84,- alternate contact d5 of relay Til), conductor d6, normal. contacts 4 7 and il-ti oi? relays RT and SR, rcs imctively, and conductor :19 to ground at alternate contact 26 of relay SLK The closing oi normal contact lelof the relay SR establishes an energizing circuit for the answering supervisory lamp AL, traced from battery through the lamp AL, over conduc tor 77, normal contact 14 of said relay, conductor 78, alternate contact 7 9 of relay SL, and conductors 80 and 81Yto ground at alternate contact 19. The two supervisory lamps AL and CL being lighted, indicate to the operator that the calling subscriber has replaced his receiver. a

Should the subscriber at the called substation B answer during" a silent period, that is. when the relay TB is in a deenernixed condition, the removal oi? the receivm.

ti 1 called substation B closes a circuit for the supervisory relay SR which maybe traced from battery through the lower Winding oi said relay Sit, conductor 32,;

normal contact 85 of; relay LD', normal,

contact-63 of relay TR, ring contacts ofthe connected plug, UP and jack J, through the now closed contacts of the substation switch book, back through tip contacts of the connected plug GP and jack J, normal contact53 of relay IR, conductor 86, normal contact 87 of relay H, conductor 88, alternate contact 89 of relay ESL, conductor 90,

1 normal contact 91 of relay LD, and through the upper winding of the relay SE to ground. The opening of normal contact l8 of the relaySR interrupts the locking circuit of the ringing control relay RC, which relay Clo-energizes to open its alternate contact 56, and the opening'of the said altering circuit for the conditioning relay l),

which relay D prepares the circuit of link disconnect relayLD so that the said relay may operate when the calling subscriber 0 and called subscriber replace their receivers. The circuit for the relay D may be traced from battery through the lamp CL, normal contact 42 0f relay RC, conductor 43, conductor ll, normal contact 15 01 relay LD, conductor 46, normal contact a7 of relay RT, alternate contact 48 of relay SR, normal contact ofrelay D, lower winding'lOl of relay D, conductor 102,11ormal contact 103 and conductor 81 to ground at alternate contact 19 otrelay SL. The

closingot alternate contact 100 of relay D closes a locking. circuit for itself; traced from battery tl'irough the upper winding 10-4, of relay D, alternate contact 100,

throughlower Winding 10-1 of relay D, conductor 102, normal contact 103, and conductor S1 to ground at alternate contactlf) oil? relay ST], i p p Should the calling subscriber answer during a ringinginterval, the ringing current is interrupted due to the actuation of the ringing trip relay RT. The circuit for relay RT extends from the ungrounded pole oi. the generator G, through the alternate contact 59, conductor 60,tl1rough the wind ing of the said relay RT, conductor 61, conductor 62, alternate contact53 of relay IR, tip contacts of the connected plug Cl? and jack J, through the now closed contacts of (hutor Gl, alternate contact (35 of relay RC,

resistance '36 and battery 67 to ground. The

removal of the receiver at the called substation D permits battery to flow through the Winding, of the relay RT to bring about the 'energization or" the relay RT The relay RT energizing opens its normally closed contact 17 to interrupt the lockingcircuit of the ringing control relay The relay RC restoring disconnects the ringing interrupter I from relay TR to preventfurther applications of ringing current to the called line. The closing of normalcontacts 53 and 63 of the relay IR brings about the energization of the supervisory'relay SR, as previously described, and-the closing of alternate contact 48 of relay SR energizes relay D,as above described. a

The called and calling subscribers at the substations A and B are now in conversational circuit, the talking circuit being traced over the heavily marked conduc' tors, After the subscribers have finished conversation, they replace their receivers upon theirrespective switch hooks, causing the supervisory relays SR and SR to restore, due to the opening of the switch hook contacts at the respective substations. .-The relay SRupon restoring closes its normal contact 1 1-, establishing. an energizing circuit to]; the link disconnect relay Ll), traced from batterythrough the Winding of the said relay, normal contact Mot relay SR, conductor 78,; alternate contact 79 of relay SIJ, and conductors 80' and 81 to ground at alternate contact 19 of relay SL. The relay Ll) energizing disassociates the calling line from the strands of the link circuit and closes a locking circuit for the relay SL, said locking circuit otthe'relay SL-being traced frombattery through the Winding 2, alternate contact f SL, conductor a, alternate contact 5 of relay LD, conductor 82, normalcontact83 of the key K, conductor 78, alternate contact '79 of relay SL, and conductors and 81 to ground at alternate contact 19 of the sleeve relay SL. The called subscriber restoring his receiver upon the switch hook opens the energizing circuit of the supervisory relay SE at the switch hook contacts, and the restoration of the supervisory relay SR, as above'de'scribed, brings about an energizing circuit for the link disconnect relay,

LD, traced from battery through the Winding of the said relay Ll), alternate contact 92 of the relay D, conductor 93, alternate.

contact 94: of relay SL, conductor 95, conductor 77 ,normal contact 14: of relay Sit, conductor 78, alternate contact 79 and conductors 80' and. '81 to ground at alternate contact 19.0t' sleeve relay SL. The relay LD energizing disassociates the called line. from the link conductors of the cord circuit C, and the closing of alternate contact 91 of the relay LD establishes a locking cirestablished the co;

,cuit for the sleeve relay SL, traced from oil relay GO ofthe link circuit L.

The opening of normal contact 380i the relay LD opens the initial energizing circuit or the sleeve relay SL, SL, being slow to release, holds up momentarily, allowing the substitute locking circuit to be established through the alternate contact 91 of the link disconnect relay Ll)- The closing of normal contacts 14: andS of the supervisory relays SR and SR brings about the lighting of the answering and callingsupervisory lamps AL and CL, as previously described. I

The operator noting the two lighted nals removes the answering plug AP and calling plug C? from their respective acks J and J, and the removal ofthe plugCP from the, jack ll" of the called line opens the energizing circuit of the sleeve relay Si, and the opening oi alternate contact 19 of the sleeve relay Slit opens the energizing circuit of the link disconnec relay LI) and the sleeve relay SL The opening of alternate contact 19 also opens the locking circuit of the relay D, and the relay D upon its energization opens the circuit of the link disconnect circuit LD at alternate contact 92 of the relay The opening of alternate contact 26 or the relay SL opens the circuit of the calling. supervisory larnp Cit and the opening alternate contact 19 of relay Slat opens the circuit of the answering supervisory lamp AIL The operator Withdrans the answering plug All? from the jack J and the apparatus used in es 'gablishing a connection between the calling subscriber A and the called subscribed B is now at nornn and available for establishing other eonnectu ritssuming now that I. 3 subscribers at the calling and called substations A and B have finished conversation, and before the plugs AP andCP have been Withdrawn i rom their respective jacks J and J the subscriber at the substation it wishes to recall, the re moval of the receiver at the substation A brings about the energization of the line relay LR of the line circuit L and the closure of the alternate contact of relay LE brings about the lighting of the multiple line signals S. The recall as initiated by the subscriber at the substation A may be seized bv the operator Who handled the ini" l I nection, or by an operator at another position.

Assuming that :e operator ho originallv iection es the rec the said operator associated with the corn but the relay 1 1,440,112 i l i circuit C actuates the recall hey K andthen Withdraws the calling plug GP from the jacl: of the called line.

K opens the locking circuit ot the relay f at the normal contact 83 of the hey l; and

the re Lilli upon ie-energizingopens its alternate contact 79 to open the energizing; circuit of the link disconnect r lay LD. The opening of normal contact 102) of the key l; opens the circuitof the relay D. The relay Ll) upon restoring to no rmalclosesits normal contacts 10 and 11, again closing the cord conductors; The closing of normal contact 5 oi relay LD again establishes an enei gizinp; circuit through the sleeve relays Fill and the cut-oil relay C0 of the line circuit L traced from battery through the Wind ings 2 and 3 of therelay Slito ground. at cutoff relay CO, as previously described, and the closing of alternatecontact'? of the relay S11: establishes a circuitthrough the lon resistance Winding of relay SL which shunts the high resistance Winding 3 or the said relay SL to prevent a second operator from seizing the call, as alread vdescribed.

The energization of relay Ci.) opens the circuit of the relay LR which restores and ei'laccs the multiple line sienals S. The closing of alternate contact 8 of relay 8L establishes an energizing circuit for thesupen. visory relay SR over the line. The calling plug Cl? having been removed brings about the de-energization of the sleeve relay SB, and the closing or" its normal contact 19 again establishes an energizing circuit for the listening relay LS as previously described. nectedto the cord conductors and she can now inquire the Wants of the recalling sub-- scriber at the substation A. The operator new tests the line Wantedby the recalling subscriber and the connection from this point is thesanic as previously described,

and a ttl'lrther description is not deeined uec nect the operators set'll to the cord con Sill e ldhould another operator other than. the one use ciated with the cord circuit U answer the recall before the operator oi. the cord circuit C can some it, the lowresistance path through the winding of the sleeve relay SL of the second cord that is connected to the recalling line prevents the relay SL oi the cord circuit C from operating tor the reason as already describech and'the operator at the cord circuit C 'iailingto receive a response knows that the call has been an swered and Withdraws the plug AP "from the jack J.

Again assuming that the subscribers at The actuation of the key The operators set is new con the cord circuit Q should, preferably, r move the calling; plug i roni the ack of the called line. However, the operator at the cord circult C may some the call, oran operator as 7 sociated with another cord may seize it. The

operator associated with the cord circuit C in seizing thecall actuates the key K and the opening or? normal contact i053 ot' the key K allows the relay D to restore to normal; and the opening of alternate contact 92 of the relay D opens the energizing circuit for the link disconnect relay Ll) and the f closing of normal contacts 85 and 185 elosesthe' continuity of the cord conductors. The opening of alternate contact 91 of relay Ll) opens the circuit of the sleever'elay to ground at normal cont-act96of the cut-on" relay CG. The sleeve relay SL, being slow torelease is momentarily held energized to again close a series energizing circuit for the sleeve relay SL and thecut-ofi? relay 0O circuit being traced from battery through the Wind ing of the relay Sl conductor 37, normal contact 38 of the relay LD', conductor 39, normal contact 40, conductor ll, sleeve con tacts oi the connected plug CPand jack 5', through the Winding of the relay CO to ground; The opening oi' nornial contact :83 of the key K opens t ie en. Zing circuit of the sleeve relay Si), and the opening of its alternate'contact 79 opens the energizing f circuit of the link disconnect circuit L1). The relay Ll), upon de-energizing again closes the circuit for the sleeve relay Sl) to ground throu h the ci'it-ofi relay CD, as previously described.

The lreyl l being actuated, acircuit for the listening relay LS is established to con{ ductor, traced lilOlllbilt ti tllro rli the up per winding of the relay lino, conductor Il2l, alternate contact 122 of key Ili con ductor 123 conductor 12%; normal contact 48 o'? relay SR, whichisnow at normal, 1111- til disconnect relay LD (lo-energizes and connects relayfilt to the subscribefis line, and conductor 49 to ground at a ternate contact 26 of relay SL. A circuit isalso estab lished through the lower Winding 16 of the listening: relay LS from battery through the Winding 16, conductor 17 alternate" contact 15, conductor 18,- conductor 125, a ternate contact 126 conductor 77, normal contact 1%, v conductor '78, alternate contact 79 of relay SL; and conductOrsSO and Bite/ground at alternate contactil) 0rrelay SL. f The listoning relay LS, upon energization, closes its alternate contacts 20 and 21 to connect the operatoidsset to the cord conductors, and

she may now'inquire thewants of the calling 7 subscriber at thesubstation B. The reestablishment of a connection from the calling subscriber at the, substation B with that of another subscriber is readily apparent from the previous description. Should a second operator seize the'call as initiated by the subscriber at the. called substation B, she

merely plugs into a multiple jack J with the answering cord of one of her cordcircuits.

will not be able to energize the relay SL of her cord circuit due to the battery potential upon the sleeve of the multiple jack J from the first operators cord circuit. However, it

nosuch potential is found, the second operator inserting her answering plug into multiple ack of the l1ne places a battery potentialupon the sleeve of the pick J to which the calling plug CP of the cord circuit C is still connected This closes an energizing circuitfor relay H-,'the circuitv of relay H being traced from ground,-through the windk ing of relay H, conductor 127, alternate contact 38 of relay LD, normal contact 4L0 of relay H, conductor L1, and the sleeve contact of the plug C]? to battery at the sleeve ofth'e jack J. Theclosing of alternate contact 87 of the relay H closes a substitute energizing circuit for the sleeve relay SL whosecircuit was opened at the normal contact 87 due to p the energization of the relay The substitute circuit for'relay SIK extends from ground through alternate contact: 87 of relay H over conductor 88, alternate contact 89 oi relay SL, conductor 90, alternate contact 91 of relay LD, conductor 37, and through the winding of relay SL to battery and ground. The sleeve relay SL is thus held v operated over this substitute path, should a second operator seize the call otthe substation B to hold certa n of the; relays of the cord circuit C in an actuated position until the operator atthe cord circuit .C withdraws the plugs Al and CP from their connected jacks to restore the. apparatus of said cord circuit C to normal. The relay H upon energizing closes a locking circuit foritsclt direct to the sleeve of the jack J. Relay H energizing also closes a circuit for relay D.

From the above description, it may be seen that'the subscriber at the-called sub station may only call after the calling sul If the call has already been seized; by the operator at C, the second operator venting a circuit from being closed through the link disconnect relay LD. LD remaining at normal, the cord conductors are not opened, and this prevents the line circuit from being disassociated from the cord circuit C, and relay LR fails to operate, thereby preventing the lighting of the multiple line signals S.

lVhile I have described my invention operatingin connection with a certain circuit arrangement, I do not wish to be limited to the same as changes and modifications may readily suggest themselves to those skilled in the art and 1 therefore a m to cover all such changes and modifications as come within the spirit andscope of the appended claims.

lVhat I claim as new and desire to secure by United States Letters Patent is:

l. A telephone system including a calling subscribers telephone line and a called sub.- scribers telephone line, a link circuit tor connecting said lines, an operators telephone, automatic means for connecting'said operatofis telephone to, and :or disconnectd lngsaid operatofis telephone from, said link circuit, and means controlled jointly by said a The relay connecting said lines, an operators tele-' phone, automatic means for connecting said calling subscriber for disconnecting his line from said link circuit,- and means controlled by said called subscriber for-disconnecting his line from said link circuit.

3. A telephone system includinga pair of subscribers telephone lines, a link circuit for connecting said lines, an opera-tors telephone, automatic means for connecting said operators telephone to, and for disconnecting said operators telephone from, said linh circuit, automatic ringing means for said link circuit, operator controlled means for associating said automaticringing means with the called one of said subscribers lines, means controllable by said opera-torcontr lled means for insuring thatjthe called subscriber will receive a, ringas soon as said operator controlled means is operated, and subscriber controlled means for disconnecting said called subscribers line from said link circuit, said last-means being operable when the phone, automatic means for connecting said llO operators telephone to, and for disconnecting said operator s telephone. from, said link circuit, automatic ringing means for said link circuit, operator controlled means for associating said automatic ringing means With the called one of said subscribers lines, means controllable by said operator controlled means for insuring that the called subscriber will receive a ring assoon as said operator controlled means is operated, means controlled by said calling subscriber for c isconnecting his telephone from said linkcircuit, and means controlled by said calling subscriber for disconnectingthe called subscribers line from said link circuit. i

- 5. A telephone system including a pair of subscribers telephone lines, a link circuit for connecting said lines, link circuit means for preventing said link circuit from connecting to a line it another link circuit is opera-- tively connected to the line, subscriber controlled means controlledover one ot said lines independent of any control exercised over the other line for disconnectingsaid link circuit from said subscribers line, link disconnect means associatedwith the calling end of saidlink circuit, subscriber controlled means controllable over the other or" said lines ior cpnditionmg sa d disconnect means for disconnecting sa d link circuit from said other line, said last means being operable necting to a line ifanother link circuit is operatively connected to the line, subscriber controlled means controlled over one of said lines independent oi theother line for dis connecting said link circuit from said sub-' scribers line, subscriber controlledmeans controllable over, the other of said; lines for conditioning meansitor disconnecting said link circuit from said other line said last meansvbeing under the joint control ofsaid subscribers. H

7. A telephone system including a pair of subscribers telephone lines, a link circuitfor connecting said lines, link circuitmeans] for preventing said link circuit from connecting to a line if another link circuit is operatively connected thereto, subscriber controller means for disassociating saidsubscribers lines from said link circuit, the .meanslfor disassociating one of said subscribers lines from said link circuit being entirely under the control ofoneofsaid subscribers, While the means for disassociating the other of ,said subscribers lines, from said link circuit is under the oint control of both of said 1 subscribers.

of subscribers? telephone lines, a circuit for connecting said lines having sleeve relays, electromagnetic. means solely under thelcontrol'ot one of said subscribers for disassociating his linecircuit from said link circuit, automatic means for disasso'ciating saidlink circuit from the other of said subscribers lines, said automaticmeans being undergthe joint control of both of said subscribers, and means for maintaining said sleeve relays energized Whensaid lines are disconnected from said link circuit. I 9. A telephone system including a calling subscribers line and acalled subscribers line, a link circuitprovided With manuallycontrolled terminals for connecting; said lines, sleeve relays, for said link circuit, electromagnetic meansunder the sole control of thecalling SUbSCIlbGDl OI disconnecting lhls line fromsaid link circuit, electromagnetic meansunder the joint control vof the callingand called subscribers for dis:

connecting said link ClI'CHl'tgfi'OIIl saidcalled subscribers. line, and means for maintaining said sleeve relays energized when said lines are disconnected from said link circuit. 10. A telephone system including a pair of subscribers lines, alinkcircuit tor con-- necting said lines, terminals for saidlink circuit, talking conductors normally con necting contacts ofjsaid' terminals, automaticfmeans for disconnecting said sub 'scribers lines-from said link circuit, only one of saidsubscribers beingable to actuate sa d automatic means to disconnect SfilChSHbSGllbOIS l nes from said link 011' cuit. 1 7

ll. A telephone system including a pair of subscribers lines, a link circuit torcon necting said lines, automatic means for disconnecting said link circuit from one of said lines an o eratorstele hone a listening relay for said link circuit, means responsive to connection of saidlink circuit to a calling one of saidlines toenergize said listening, relay to connect the operators set to the llnkcircuit, means responsiveto the connection of said link circuitqto a called one of said lines tor deenergizing sa d relayto disconnect theoperator s set fromsald .linkycircuit, automatic means for disconnesting saidlink circuit from the other of vsaid lines, said first automatic means being controllable at the Wlll o l one of, said subscribers, and said second, automatic means being under the oint control of both ofsaid subscribers. p i ,1 12. A telephone system includinga call-i vingand a called subscriberstelephoneline,

a link circuit for eonnecting said lines, an operatorls telephone, a listening relay for saidvlink circuit, 'meanshresponsive to connection of I said I link circuit to i a calling one H a of said lines to energize said listeningrelay 8. A telephone system includinga pair p cuit, means responsive ,to the connection "of to connect the operators setitothellink cirs sai'd link circuit "to a callcd one of said lines l? for de-energizi-n'g" saicl relay to '*'disconnect the operat'ors set from;= sa1d I link circuit, subscriber controlled "means-r "for dis-- connecting said calling subscribers -li'ne from said linkpimuit, automatic -means *for' tion 'of a second-link circuit 'to a calling} subscribers line when answening a call therefrom ifthe first link circuit is -operatively connected to said subscribe'r s li-ne to answer a 1 call therefrom,- 1 automatic means 1 fordisa connecti-ng said link circuit from said call- ":fordiseonneetin s 5 5 in-g subscribers line, automatic means for. disconnecting said link circuit from said called subscribers line, said fi-rst means being operablewvhen? the calling'subsc'riber replaces his receiver, and said second means being also operable when the *callingsubscriberreplaces his'receiver. ii telephone system including a calling subscribers 1ine andacalled subscribers line, a link circuit for connecting-said lines, movable: terminals for said lin'k=circu it,-talking strands for said A link circuit norinally connecting contacts of said terminals, sleeve relays for said link circnit,'=automatic means solely under the' control of -saidgcall ingsubscriber for disconnecting sa'id link' circuit irony said" calling subscribers line independent of any" means controlled "over the other subscribers line-, automatic means con-- callable- "by said calling subscriber for disc'onne'ctingsaid called subscribers line from said "link circuit, and-means 1' for maintaining said sleeve relaysenergized after the subscribers lines have "been disconnected from'the link' circuit. a T 515; telephone system including a call- 1 ing subscribers lineaiid acalledsubscribers line," a link circuit for"connectingsaid lines "having sleeve "relays; automatic 'i'ne'a'nsj 'und'er the control ofsaidvcaH-ing--subscribe1- link circuit i from said "calling" subscribers linefiaiitoniati --in'ea'ns controllable by said calling subscflber or idisconnectingsaid' "cal-led subscribersline "from said link circuit, 1 said *la'st means-be j ing "controllable "by said calling subscriber only after said'icalled"subscriber has conditione d a relay for operation', arrd means-for maintaining said sleeve relays f f "energized after 1 theljsubscribersy lines-"have been dis 'connected"fromftheiriink circ iit.

163'A"teiepirone'system'mclutling-a eallt 'nection for-disc I subscribers'line,'n1eans in said link "circuit "operable responsive to the connection of a ing'subscribers line and a calledsubscribers line; a link circuit for connecting said lines, automatic means for disconnecting said ca'lled'subscribers line from said link Vcircuit, and a relay in said link circuit operable'responsive to the connection of another link circuit to said called subscribers line;

17. A telephone system including a called subscribers telephone line, a link circuit for from said subscribers line, thereby rendering said subscribers line available 1 for con- 'nect1on,a'relayfor said link circuit, and means responsive to the connectlon' of a second l'ink circuit to saidsubscribefs line to operate saidrelay- 19. 'A'telephone system including a subscribers telephone line, a link circuit for connection thereto, subscriber a controlled means for disconnecting said link circuit from said subscribers line,thereby rendering 'said subscribers'line available for connectio-n, a relay for said link circuit, and means responsive to the connection of a second link circuit-to said subscribefis line to operate said relay, said relay upon" enercontrollable by the second of saidlink circuits.

20. A telephone systemincludinga called subscribers telephone line,a link circuit for connection thereto, subscriber controlled {means *for disconnecting said link circuit fronrsa1d subscribers l1ne,thereby rendering said'subscribefls line available'for connection, a=relay for said link circuit, and *rnieans responsive to the connection of a second link circuit to said subscribers line to operate said relay, said relay being operableto. prevent said first link circuitfroni beingagainassociated with said subscribers "line.

21, A; telephone system including subs' 'telep hdne" line, a link circuitfor conhereto, subscriber controlled'ineans nectim saidlink circuit from said second linkci'rc'uit to said subscribers line,

saidineansbeing operable to preventinterference with the connection of'said second link circuit to said subscribers line.

v22. A telephone system including a called subscribe'rs f teleplro11cv line," a; link circuit for connect1on theieto,"'inoitab1e "terminals for gizingdclosing a loclzing'circuit'for itself" giaonie said link circuit, talking strands for "said link circuit normally connectingcontacts of said terminals, subscriber controlled automatic means for disconnecting said link circuit from said line, and means for said link circuit associated with and controlled over the calling end oi said link circuit and" operable b ythe connection of a second link circuit and sa d line for preventing said first link circuit from again being opera tively associated With said line.

23.. A telephone system includ ng a subscribers telephone line, a link, circuit for connection thereto, subscriber controlled automatic means for disconnectlng said link circuit from said line, and means for said link circuit for preventing said link circuit from again being operatively associated with said line,saidlast means being operat-i second ed responsive to the connection of a link circuit to said line;

24; A telephone system including a calling subscribers line and a called subscribers line, a link circuit for connecting said lines, means controlled jointly by said calling and called subscribers for disassociating said link circuit from one of said lines,

a relay for said linkcircuit, and a circuit for said relay controllableby the connection of a second link circuit to one of saidsubscribers lines.

25. A telephone system including a call.

ing subscribers line and a called subscribers line, a link circuit for connecting said lines, means controlled jointly by said calling and called subscribers for disassociating said link circuit from one of said lines, a relay for said link circuit, and means responsive to the connection of a second link circuit to one of said subscribers lines to operate said relay. said relay upon ener gazing closing a locking circuit for itself to prevent said first link circuitfrom being again associated with the said subscribers line.

25. A; telephone systemincluding a pair of subscribers? telephone lines, a link circuit for connecting" said lines, subscriber-i controlledzineans controlled over one of said lines for disconnecting said link circuit from said subscribers line, subscriber-con trolled means controllable over one of said lines for disconnecting said link circuit from the other line, saidlast means being oper able when said first line signals for disconnection, a relay for said link circuit, and a circuit for said relaycontrollable by the connection of a second link circuit to one of said linesi 27. A telephone system includinn'a pair of subscribers telephone lines, a link circuit for connecting said l1nes,electromao;- netic means-under the control of one of said cuit from said link circuit, automatic means for disassociatingsaid link circuit from the subscribers for disassociating his line cir of subscribers 'telephone linesga link ,cir-

cuit for connecting said lines, electromagnetic means under the control of said subscribers for disassociating their lines from said link circuits, a relay forsaid link circuit, and means responsive to the connection of a second link circuit to one of said lines for energizing said relay.

Signed by me at Chicagdin the county of 7 Cook and State of Illinois, this 28th day of a i p June, 1918.

CHARLES SPARKS. 

